During radiation therapy, the radiation is delivered in a targeted beam to the tumor. However, due to normal physiological function, the patient's body is in constant motion. Breathing and heart function cause the body, and in particular the chest and the abdomen, of the patient to move. The constant motion can distort target volumes and result in positioning errors, particularly in abdominal, lung, liver, and breast cancer tumors. It is estimated that abdominal tumors move approximately 2 millimeters, while lunch tumors move on average from 3 to 22 millimeters during breathing. Bucsko, J. K. “Managing Respiratory Motion”, Radiology Today 5(23):33 (2004). It is therefore desirable to immobilize tumors prior to and during the radiation therapy.